A study of the Prins reaction will be undertaken and the effect of neighboring groups on the steric aspects of this rection will be ascertained. Utilizing the Prins reaction the stereoselective synthsis of podophyllotoxin, picropodophyllin, and other components of podophyllum will be investigated. A structure-activity relationship study with respect to the antimitotic action of the podophyllums will be performed. Simplified analogs of podophyllotoxin will be prepared and tested for their antitumor effect. Bioisosteres of the parent compounds will also be prepared and assayed.